A newly graduated lawyer named Masami Takeda begins her career at a small law firm in Tokyo, where she is unexpectedly teamed up with Motohito Kuzu. Kuzu is an experienced and highly unorthodox attorney whose sharp tongue and ruthless tactics have earned him the nickname the scum of lawyers from his peers. Despite his abrasive personality and questionable ethics, which often involve manipulation and exploiting legal loopholes, Kuzu possesses a brilliant legal mind and a deep, if unconventional, commitment to achieving the best outcome for his clients. The series follows this mismatched pair as they take on a wide variety of challenging civil and criminal cases, with the idealistic and by-the-book Takeda constantly learning from and clashing with her unscrupulous mentor.

The central conflict of the story arises from the fundamental difference in philosophy between the two main characters. Takeda believes in justice and the spirit of the law, while Kuzu operates on the cynical belief that a lawyer's sole job is to win, using the letter of the law as his weapon. This dynamic forces Takeda to confront the harsh realities of the legal world, where the truth is not always clear-cut and winning often requires more than just moral righteousness. The supporting cast includes the firm's elderly and wise senior partner, Makoto Shiraishi, and other legal professionals like the ambitious prosecutor Yujiro Kunimitsu, who serves as a recurring rival. The setting is grounded in the everyday reality of Japanese legal practice, from small claims disputes to more serious criminal defenses, all handled within the firm's modest offices and the local courthouse.

The narrative is structured as a series of self-contained episodes, each focusing on a specific client and legal dilemma. Early arcs establish the core relationship between Takeda and Kuzu, introducing the latter's methods through cases involving divorce, debt collection, and petty crime. As the series progresses, the cases become more complex and high-stakes, exploring themes of corporate liability, inheritance battles, and wrongful imprisonment. Through each case, Kuzu's seemingly callous strategies are revealed to have a deeper logic, often serving a form of rough justice that the system itself fails to deliver. A notable element of the series' history is a copyright infringement lawsuit filed against the author in 2008 by a Tokyo lawyer who claimed plagiarism, a case that was ultimately resolved in the author's favor.